1. Field of the Invention
The present invention relates to multi-head sewing machines and, in particular to multihead sewing machines for repeatedly performing sewing operations, e.g., embroidering operations, onto long workpieces having a predetermined width and longitudinal direction. The present invention also relates to methods of feeding long workpieces in multi-head sewing machines.
2. Description of the Related Art
Multi-head sewing machines are known that are used for embroidering patterns onto long workpieces along the length of the workpieces. The embroidery patterns may be continuous along the length of the workpieces (hereinafter called “continuous patterns”) or may not be continuous while the same patterns are intermittently embroidered along the length of the workpieces (hereinafter called “intermittent patterns”). In general, the long workpieces are partly held by embroidery frames in order to embroider “continuous patterns” or “intermittent patterns”. During the embroidering operation, the embroidery frame is moved in an X-direction and a Y-direction within a plane above a machine table. The X-direction and Y-direction are perpendicular to each other. After the embroidering operation have been performed onto a part of a workpiece that is held by the embroidery frame, the workpiece is released from the embroidery frame and is fed in the longitudinal direction by a predetermined distance. Then, another part of the workpiece next to the part that has been embroidered is held by the embroidery frame and the embroidering operation is again performed. These operations are repeatedly performed to embroider a continuos pattern or intermittent patterns.
Japanese Patent Publication No. 61-5744 discloses a multi-head sewing machine that has a feeding mechanism for feeding a long workpiece that is embroidered in the same manner as described above. The feeding mechanism includes a workpiece supply stand, on which a long workpiece is stored in a rolled configuration, and a workpiece recovering stand for winding the long workpiece that has been embroidered. The workpiece supply stand and the workpiece recovering stand are disposed in forward and rearward positions with respect to a Y-direction that is perpendicular to an X-direction. Sewing heads are arranged in a row in the X-direction. Therefore, the workpiece is fed in the Y-direction that is perpendicular to the X direction, i.e., the direction of the row of the sewing heads. After the embroidering operation has been performed onto a part of the workpiece that is held by an embroidery frame, the embroidery frame is moved to a maximum forward stroke end in the Y-direction while the embroidered part is held by the embroidery frame. The embroidered part is then released from the embroidery frame, so that the workpiece returns to the original position in the Y-direction. Thereafter, the next part of the workpiece is held by the embroidery frame and the embroidering operation is again performed onto the next part.
As described above, in the known multi-head sewing machine, the workpiece is fed in the direction that is perpendicular to the direction of the row of the sewing heads. In addition, embroidery frames of multi-head sewing machines generally have widths that are greater enough than widths of workpieces to be embroidered. Therefore, two or more long workpieces are set onto an embroidery frame such that they are arranged in an X-direction with respect to the embroidery frame. With this arrangement, a maximum number of the sewing heads can be operated in order to perform the embroidering operation. Therefore, this arrangement is particularly effective for the purpose of mass production. However, in recent years, large item small scale production has become a mainstream of production of embroidery products. The known technique as described above is inefficient for this mainstream production in some cases.